Synchronous sampling of rotating elements in a fault detection system having audio analysis and method of using the same

ABSTRACT

A fault detection system for determining whether a fault exists with a rotating element of a vehicle. The system includes a transducer, a diagnosis sampler, a sensor, and a controller. The transducer may be a microphone located in the vehicle for converting sounds to an electrical signal. The electrical signal includes a noise component generated from the rotating element. The diagnosis sampler is connected to the transducer and provides a sample of the electrical signal from the transducer to the controller. The sensor obtains data relating to the rotating element. The controller has functional aspects such as a synchronous resample, a spectrum analysis, and a fault detect. The synchronous resample has the capability of synchronizing the sample of the electrical signal with the data from the sensor to form a synchronized envelope. The spectrum analysis has the capability of forming a spectra from the synchronized envelope of the electrical signal, where the spectra is associated with the noise component generated from the rotating element. The fault detect has the capability of determining (from the formed spectra) whether the fault exists with the rotating element. There is also a method of detecting a fault associated with a rotating element in a vehicle using the above-described system.

The present application claims priority from provisional application,Serial No. 60/373,157, entitled “Synchronous Sampling of RotatingElements in a Fault Detection System Having Audio Analysis and Method ofUsing the Same,” filed Apr. 17, 2002, which is commonly owned andincorporated herein by reference in its entirety. Moreover, this patentapplication is related to co-pending, commonly assigned patentapplication, Ser. No. 10/213,784, entitled “Fault Detection SystemHaving Audio Analysis and Method of Using the Same,” filed concurrentlyherewith and incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention in general relates to the detection of faults in avehicle and, more particularly, to synchronous sampling of rotatingelements in a fault detection system having audio analysis and a methodof using the same.

BACKGROUND OF THE INVENTION

A user of a vehicle may hear an unpleasant sound or feel a strangevibration while operating a vehicle. Most users of vehicles are nottrained to know or recognize the source of such a sound or vibration andin many cases significant changes over longer periods of time are sosubtle they go undetected. Many unpleasant sounds and strange vibrationsare generated by faults of rotating elements in a vehicle such as thetires, the engine, the driveline, and the fan or blower of the heating,ventilation, and air-conditioning (HVAC) system. Accordingly, there isalso a need for aiding the user of a vehicle to identify the source ofunpleasant sounds or strange vibrations in the vehicle.

Various systems have been employed for detecting faults on a vehicle.Existing systems require dedicated sensors outside the cabin of avehicle for each component on the vehicle. These sensors are susceptibleto fault over time due to exposure to corrosive and other harshenvironments.

In the past, systems have considered using an audio transducer locatedin close proximity to a component susceptible to a fault. Such systems,however, require multiple audio transducers if there is a desire tomonitor multiple components. Additionally, these audio transducers aresusceptive to interference from sounds and vibrations of othercomponents. Furthermore, the sensors themselves may be susceptible tocorrosion and other faults if they are located in harsh environments.

Accordingly, further improvements are needed to known systems for themonitoring of multiple components on a vehicle. It is, therefore,desirable to provide an improved procedure for detecting faults ofrotating elements in a vehicle to overcome most, if not all, of thepreceding problems.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention provides a fault detection systemfor determining whether a fault exists with a rotating element of avehicle. The system includes a transducer, a diagnosis sampler, asensor, and a controller. The transducer may be a microphone located inthe vehicle for converting sounds to an electrical signal. Theelectrical signal includes a noise component generated from the rotatingelement. The diagnosis sampler is connected to the transducer andprovides a sample of the electrical signal from the transducer to thecontroller. The sensor obtains data relating to the rotating element.The controller has functional aspects such as a synchronous resample, aspectrum analysis, and a fault detect. The synchronous resample has thecapability of synchronizing the sample of the electrical signal with thedata from the sensor to form a synchronized envelope. The spectrumanalysis has the capability of forming a spectra from the synchronizedenvelope or the electrical signal, where the spectra is associated withthe noise component generated from the rotating element. The faultdetect has the capability of determining (from the formed spectra)whether the fault exists with the rotating element.

Another aspect of the present invention provides for detecting a faultassociated with a rotating element in a vehicle. This can include:sampling an electrical signal from a transducer in the vehicle where theelectrical signal comprises a noise component generated from therotating element; synchronizing the electrical signal with data from asensor associated with the rotating element to form a synchronizedenvelope associated with the rotating element; forming a spectra fromthe synchronized envelope where the spectra is associated with the noisecomponent generated from the rotating element; and determining (from theformed spectra) whether a fault exists with the rotating element.

A further aspect of the present invention provides for detecting a faultassociated with a plurality of rotating elements in a vehicle. This caninclude: sampling an electrical signal from a transducer in the vehiclewhere the electrical signal comprises a plurality of noise componentsgenerated from the rotating elements; synchronizing the electricalsignal with data from a plurality of sensors associated with therotating elements to form a synchronized envelope associated with eachrotating element; forming a plurality of spectra from the synchronizedenvelopes where each spectra is associated with one of the noisecomponents generated from the rotating elements; and determining (fromeach of the plurality of formed spectra) whether a fault exists with oneof the rotating elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a fault detection system according to oneembodiment of the present invention;

FIGS. 2A-2E are exemplary spectra diagrams for various rotating elementson a vehicle;

FIG. 3 is a block diagram of another embodiment of a systemincorporating the fault detection system of the present invention.

While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the invention is not intended to be limitedto the particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

What is described is an improved system and procedure for detectingfaults associated with rotating elements on a vehicle. To this end, inone embodiment there is a fault detection system for determining whethera fault exists with a rotating element of a vehicle. The system includesa transducer, a diagnosis sampler, a sensor, and a controller. Thetransducer may be a microphone located in the vehicle for convertingsounds to an electrical signal. The electrical signal includes a noisecomponent generated from the rotating element. The diagnosis sampler isconnected to the transducer and provides a sample of the electricalsignal from the transducer to the controller. The sensor obtains datarelating to the rotating element. The controller has functional aspectssuch as a synchronous resample, a spectrum analysis, and a fault detect.The synchronous resample has the capability of synchronizing the sampleof the electrical signal with the data from the sensor to form asynchronized envelope. The spectrum analysis has the capability offorming a spectra from the synchronized envelope of the electricalsignal, where the spectra is associated with the noise componentgenerated from the rotating element. The fault detect has the capabilityof determining (from the formed spectra) whether the fault exists withthe rotating element.

Another embodiment of the present invention is a method for detecting afault associated with a rotating element in a vehicle. The steps of themethod include: sampling an electrical signal from a transducer in thevehicle where the electrical signal comprises a noise componentgenerated from the rotating element; synchronizing the electrical signalwith data from a sensor associated with the rotating element to form asynchronized envelope associated with the rotating element; forming aspectra from the synchronized envelope where the spectra is associatedwith the noise component generated from the rotating element; anddetermining (from the formed spectra) whether a fault exists with therotating element.

A further embodiment of the present invention includes a method fordetecting a fault associated with a plurality of rotating elements in avehicle. This steps of this method include: sampling an electricalsignal from a transducer in the vehicle where the electrical signalcomprises a plurality of noise components generated from the rotatingelements; synchronizing the electrical signal with data from a pluralityof sensors associated with the rotating elements to form a synchronizedenvelope associated with each rotating element; forming a plurality ofspectra from the synchronized envelopes where each spectra is associatedwith one of the noise components generated from the rotating elements;and determining (from each of the plurality of formed spectra) whether afault exists with one of the rotating elements.

Now, turning to the drawings, an example use of a fault detection systemfor a vehicle will be explained. As will be explained in more detailbelow, the fault detection system samples the sound in a cabin of thevehicle and uses the sampled sound as a diagnostic tool for determiningwhether a fault exists with rotating elements in the vehicle. Referringto FIG. 1, in one embodiment, a fault detection system 20 generally hasa transducer 22, a diagnosis sampler 24, and a controller 26. The faultdetection system 20 determines whether a fault or problem exists withone of a plurality of rotating elements 30 a, 30 b, 30 c in the vehicle.Examples of rotating elements 30 a, 30 b, 30 c in the vehicle includeelements such as the tires, the engine, the driveline, and the fans orblower for the heating, ventilation, and air-conditioning (HVAC) system.

As discussed in more detail below, after analysis of the sampled sound,a signal representing a fault or problem may be transmitted by thecontroller 26 to an electronic control unit (ECU) 32. The ECU 32 maythen notify the user of the vehicle via a user display panel 34 that afault or problem exists with a rotating element 30 a, 30 b, 30 c.Alternatively, or additionally, a digital signal representing the faultor problem may be transmitted via a wireless communication device 36 toa service center (shown in FIG. 3).

The transducer 22 may be a microphone located in the cabin of thevehicle. In one embodiment, the transducer 22 is a microphone used forhands-free voice calls through the wireless communication device 36. Thewireless communication device 36 is connected to the transducer 22 andto an audio speaker 38 within the cabin. The transducer 22 may also be amicrophone used for communication with a remote service center forinformation and roadside assistance. Utilizing an existing microphone inthe cabin provides the advantage of multi-tasking a single component inthe vehicle. Alternatively, a separate dedicated transducer 22 may beinstalled in the vehicle.

The transducer 22 converts sounds in the cabin of the vehicle to anelectrical signal 40. In one embodiment, the electrical signal 40 fromthe transducer 22 is an analog signal. The diagnosis sampler 24 receivesthe electrical signal 40 from the transducer 22. The purpose of thediagnosis sampler 24 is to sample the electrical signal 40 from thetransducer 22 for input to the controller 26. The diagnosis sampler 24may be a separate integrated circuit from the controller 26.Alternatively, the diagnosis sampler 24 may reside within the controller26 and be an integral part of the input. The diagnosis sampler 24 allowsthe electrical signal 40 to be further analyzed by the controller 26.

In one embodiment, the diagnosis sampler 24 takes samples of theelectrical signal 40 and converts the electrical signal 40 to a formatacceptable to the controller 26. For example, if the controller 26 is adigital signal processor (DSP) controller, the electrical signal 40 isconverted to a digital signal 42. Accordingly, the diagnosis sampler 24may include components such as an amplifier and an Analog to Digital(A/D) converter. The sampling rate should depend on the frequency limitof the transducer 22. For example, in one embodiment, the samplingprocess would be at least double the highest frequency range of thetransducer. This means that for a transducer 22 that can pick up soundsup to 6 kHz, the minimum sampling rate for the diagnosis sampler 24 is12,000 samples per second. In most embodiments, the diagnosis sampler 24should be about 16,000 samples per second and having a 12 bit resolutionfor each sample.

The diagnosis sampler 24 may be configured a number of different ways tosample the electrical signal 40 from the transducer 22. In oneembodiment, the diagnosis sampler 24 is configured to continuouslysample the electrical signal 40 at select time intervals during theoperation of the vehicle. In another embodiment, the diagnosis sampler24 is configured to sample the electrical signal 40 in response to aninstruction from the electronic control unit 32 or controller 26. Theinstruction to sample the cabin sound could be sent when certain knownconditions exist within the vehicle (i.e. when a rotating element isrotating at a certain rate). Furthermore, the diagnosis sampler 24 maybe configured to sample the electrical signal 40 or be otherwiseactivated in response to an instruction from a service center (notshown) and/or the user of the vehicle.

The electrical signal 40 generated by the transducer 22 is a compositeof sound components in the cabin of the vehicle. In one embodiment, thedigital signal 42 generated by the diagnosis sampler 24 will also be acomposite of sound components in the cabin of the vehicle.

One component of the sampled sound will be noise from rotating elements30 a, 30 b, 30 c of the vehicle. In some cases, the noise related to theactual rotation of rotating elements 30 a, 30 b, 30 c will be much lowerin frequency than the limits of the transducer 22. For instance, if thetransducer 22 is a microphone for hands-free voice calls orinformation/road-side assistance services, these microphones can onlypick up sounds between the range of 400 Hz and 6 kHz. Accordingly, thetransducer 22 may not directly pick up the noise related to the actualrotation of these rotating elements 30 a, 30 b, 30 c if they are below400 Hz. The noise associated with the rotation of a rotating element 30a, 30 b, 30 c, however, will propagate to the structure of the vehicle(such as the chassis). Noise through the structure of the vehicle ringsin response to forces generated by the rotating elements 30 a, 30 b, 30c. It has been discovered that the ringing allows a transducer 22 withlimited frequency response to detect the state of the rotating elements30 a, 30 b, 30 c even when the elements themselves are rotating slowlyrelative to the pass band of the audio system.

For example, as mentioned above, one of the rotating elements 30 a, 30b, 30 c on a vehicle may be the tires. A tire having a radius of 18inches will rotate at 560 RPM at 60 MPH. This will cause a repetitionrate of 9.3 Hz. Sounds at this frequency are too low for the microphoneto pick up much less an audible frequency for a human ear (20 Hz-20kHz). The tire assembly, however, is attached to the chassis of thevehicle. A 9.3 Hz frequency will generate a vibration to the chassis ofthe vehicle that will result in a higher frequency noise. The transducer22 will pick up the higher frequency noise from the chassis caused bythe rotating elements.

The vibration noise from the chassis is a composite of several othervibration noises caused from other sources of the vehicle. One aspect ofthe present invention is directed to associating a noise with aparticular rotating element 30 a, 30 b, 30 c from the composite ofvibration noises and analyzing that noise to determine a fault orproblem for the rotating element 30 a, 30 b, 30 c.

The controller 26 processes the digital signal 42 from the diagnosissampler 24. A suitable controller 26 for the present invention mayincludes a digital signal processor (DSP) controller or a Motorola MPC5100. The controller 26 of the present invention preferably includes anumber of functional blocks. In one embodiment, the controller has anenvelope detect 44, a synchronous resample 46, a plurality of spectrumanalyses 48 a, 48 b, 48 c, and a plurality of fault detects 50 a, 50 b,50 c. These functional blocks may be microcoded signal processing stepsthat are programmed as operating instructions in the controller 26.

The envelope detect 44 detects an envelope 52 from the digital signal 42received from the diagnosis sampler 24. The envelope 52 is generated tocapture the peak amplitude values of signal bursts and rings. This canbe accomplished by rectification of the digital signal 42 and low passfiltering. Both the rectification and the low pass filtering are donedigitally. The rectification may be done by taking the absolute value ofthe digital signal 42. The rectification process may be a mathematicalabsolute model or other digital representation known to those ofordinary skill in the art.

The rectified data is then applied to the low pass filter. The cutofffrequency used for the low pass filter is implementation specific. Thecutoff frequency will typically depend on the size of the rotatingelement (such as the size of the rotating tire). It has been found,however, that each of the rotating elements in a vehicle come within arange of 5-100 pulses per second. In a cost efficient implementation, asuitable cutoff frequency for the low pass filtering may be selectedbetween 200-400 Hz. Alternatively, separate low pass filtering may beimplemented for each of the rotating elements. In any event, as will bediscussed further, the monitoring and analysis of the envelope 52 ofcabin sounds enables the detection of faults or problems with aparticular rotating element in the vehicle.

Within the envelope 52 is a mixture of sounds from the cabin of thevehicle that were picked up by the transducer 22. Some of these soundsmay relate to possible problems of the vehicle and some may not relateto problems of the vehicle. The present invention includes a synchronousresample 46 to correlate and synchronize the noise associated withindividual rotating elements 30 a, 30 b, 30 c in the vehicle.

It has been discovered that the vibration noise from the chassis orother vehicle structure generated from the rotating elements 30 a, 30 b,30 c is closely related to the rotation of that element. Accordingly,knowing the rotation of an element 30 a, 30 b, 30 c allows thecontroller 26 to synchronize the composite envelope 52 for furtheranalysis of a particular rotating element 30 a, 30 b, 30 c.

To this end, the synchronous resample 46 receives sensor data 54 a, 54b, 54 c relating to each of the rotating elements 30 a, 30 b, 30 c. Thesensor data 54 a, 54 b, 54 c is used to synchronize the compositeenvelope signal 52 for a particular rotating element 30 a, 30 b, 30 c.The sensor data 54 a, 54 b, 54 c is obtained from sensors 56 a, 56 b, 56c, respectively, located at each of the rotating elements 30 a, 30 b, 30c.

In one embodiment, the sensor data 54 a, 54 b, 54 c is representative ofthe angular displacement of the rotating elements 30 a, 30 b, 30 c.There are a number of ways to measure the angular displacement of anelement. In one embodiment, the sensors 56 a, 56 b, 56 c measure apassing tooth 58 a, 58 b, 58 c, respectively, on a rotating wheel of therotating element 30 a, 30 b, 30 c. For example, a sensor may measure apassing tooth on a rotating wheel attached to an engine's crankshaft. Asthe engine runs, the sensor typically generates a logic level signalthat transitions when the sensor senses the tooth and a subsequentspace. As the toothed wheel rotates, responsive to the combustionprocess in the running engine, the angular displacement signal willtypically be a rectangular waveform responsive to angular velocity, orengine speed. The practice of using a toothed wheel on a crankshaft andother rotating elements is commonplace in the field of vehicle control.Of course, those skilled in the art will recognize many other,substantially equivalent, means and methods to measure angulardisplacement.

The sensor data 54 a, 54 b, 54 c is provided to the synchronous resample46. The sensor data 54 a, 54 b, 54 c is used to synchronize thecomposite envelope 52 to generate synchronized envelopes 60 a, 60 b, 60c associated with each rotating element 30 a, 30 b, 30 c. Accordingly,the synchronized envelope 60 a relates to rotating element 30 a. Thesynchronized envelope 60 b relates to rotating element 30 b. Thesynchronized envelope 60 c relates to rotating element 30 c. Eachsynchronized envelope 60 a, 60 b, 60 c is then further analyzed by aseparate spectrum analysis functional block 48 a, 48 b, 48 c.

In one embodiment, the resample of the composite envelope 52 includesgiving the envelope signal a new scale (sampling period). For example,the composite envelope 52 may have a sampling period of 16,000 samplesper second. There is a need to resample this envelope at a differentrate depending on the rate of the rotating elements 30 a, 30 b, 30 c.The synchronous resample 46 forms a synchronized envelope 60 a, 60 b, 60c depending on the rotating rate of the rotating elements from thesensors 56 a, 56 b, 56 c.

The rotating element 30 a in one embodiment may be a tire on a vehicle.Associated with the tire is an anti-brake system (ABS) sensor 56 a thatcan generate data that can be used to determine the rotational rate ofthe tire at a particular time. The ABS sensor 56 a will transmit data 54a to the synchronous resample 46. The synchronous resample 46 receivesthe data 54 a from the ABS sensor 56 a. The ABS sensor data 54 a is thenused as the sampling clock to synchronize the composite envelope 52 togenerate a tire synchronized envelope 60 a for the tire spectrumanalysis 48 a. The tire spectrum analysis 48 a may then use the tiresynchronized envelope 60 a as described in more detail below.

Moreover, the rotating element 30 b may be the engine of the vehicle(such as a V6 engine). Associated with the engine is a crankshaftposition sensor 56 b that can generate data that can be used todetermine the rotational rate of the engine at a particular time. Thecrankshaft position sensor 56 b will transmit data 54 b to thesynchronous resample 46. The synchronous resample 46 receives the data54 b from the crankshaft position sensor 56 b. The crankshaft positionsensor data 54 b is then used as the sampling clock to synchronize thecomposite envelope 52 to generate an engine synchronized envelope 60 bfor the engine spectrum analysis 48 b. The engine spectrum analysis 48 bmay then use the engine synchronized envelope 60 b as described in moredetail below.

Furthermore, the rotating element 30 c may be the driveline of thevehicle. Associated with the driveline is a vehicle speed sensor 56 cthat can generate data that can be used to determine the rotational rateof the driveline at a particular time. The vehicle speed sensor 56 cwill transmit data 54 c to the synchronous resample 46. The synchronousresample 46 receives the data 54 c from the vehicle speed sensor 56 c.The vehicle speed sensor data 54 c is then used as the sampling clock tosynchronize the composite envelope 52 to generate a drivelinesynchronized envelope 60 c for the driveline spectrum analysis 48 c. Thedriveline spectrum analysis 48 c may then use the driveline synchronizedenvelope 60 c as described in more detail below.

The present invention is not limited to analysis of the tires, engineand driveline but may include other types of rotating elements such asthe fans or blowers in the HVAC.

Additionally, it is noted that the synchronous resample 46 aids in theanalysis of vehicle cabin noise when the rotational rates of therotating elements is changing over time. The frequency spectrum of thecabin sound will show many features related to the rotation of elementson the vehicle. As indicated earlier, rotating elements such as thetires, the engine, the driveline, and the HVAC blower lead to cabinnoise. Most of the rotating elements in a vehicle vary in speed duringthe operation of the vehicle. If samples are taken at regular timeintervals (regardless of vehicle operation), the time sampled spectrumwill change as the rotational speed of the element changes.Synchronizing the composite envelope 52 with data 54 a, 54 b, 54 cobtained from sensors 56 a, 56 b, 56 c at the rotation elements 30 a, 30b, 30 c solves the problem of varying rotational speeds duringoperation.

There is a separate spectrum analysis function 48 a, 48 b, 48 cperformed for each rotating element 30 a, 30 b, 30 c on the vehicle. Inone embodiment, the spectrum analysis uses DSP based techniques and, inparticular, uses the Fast Fourier Transform (FFT). FFT techniques, asapplied to digitized data, provides a powerful method of signal analysisby having the ability to recognize weak signals of defined periodicityburied in a composite signal.

In one embodiment, the present invention uses FFT techniques to generatespectra that is “order” based as shown in FIGS. 2A-2E. The “orders”shown in the figures are defined as a sine wave cycle per revolution. Ithas been discovered that noise generated from rotating elements comesout at predictable orders. In other words, the amplitude of the noise isparticularly predominating at certain cycles per revolution. This aidsin determining whether a fault or problem exists with a particularrotating element 30 a, 30 b, 30 c.

For example, if the spectrum analysis 48 a is designed to analyze tirefaults, the spectrum analysis 48 a may generate an “order” based spectraas shown in FIG. 2A. Referring to FIG. 2A, a rotating tire haspredictable peak amplitude spikes at orders 1-2-3-4. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 102 a-102d refer to amplitude spikes that are consistent with a rotating tirethat does not have a fault or problem with balance or suspensionlooseness. The dashed line amplitude spikes 102 a′-102 d′ refer toamplitude spikes that are consistent with a rotating tire that has afault or problem with balance or suspension looseness. The amplitudespikes 102 a′-102 d′ associated with a fault or problem are greater thanthe amplitude spikes 102 a-102 d associated with normal tire rotation.

If the spectrum analysis 48 b is designed to analyze engine faults (suchas a V6 engine), the spectrum analysis 48 b may generate an “order”based spectra as shown in FIGS. 2B and 2C. Referring to FIG. 2B, anengine has predictable peak amplitude spikes at orders 1-2-3 whendetermining whether the engine has a balance problem. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 104 a-104c refer to amplitude spikes that are consistent with an engine that doesnot have a fault or problem with balance. The dashed line amplitudespikes 104 a′-104 c′ refer to amplitude spikes that are consistent withan engine that has a fault or problem associated with engine balance.The amplitude spikes 104 a′-104 c′ associated with a fault or problemare greater than the amplitude spikes 104 a-104 c associated with normalengine operation.

Referring to FIG. 2C, an engine also has predictable peak amplitudespikes at orders 3-4-9 when determining whether there is exhaust noise(such as a leaky muffler). The peak amplitude decreases as the orderincreases until the harmonics are insignificant compared to systematicnoise. The solid line amplitude spikes 106 a-106 c refer to amplitudespikes that are consistent with an engine that does not have a fault orproblem with exhaust noise. The dashed amplitude spikes 106 a′-106 c′refer to amplitude spikes that are consistent with an engine that has afault or problem associated with exhaust noise. The amplitude spikes 106a′-106 c′ associated with a fault or problem are greater than theamplitude spikes 106 a-106 c associated with normal engine operation.

If the spectrum analysis 48 c is designed to analyze driveline faults,the spectrum analysis 48 c may generate an “order” based spectra asshown in FIGS. 2D and 2E. Referring to FIG. 2D, a driveline haspredictable peak amplitude spikes at orders 1/n, 2/n, 3/n, where n isthe numerical ratio of the gearing for the rear axle. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 108 a-108c refer to amplitude spikes that are consistent with a driveline thatdoes not have a fault or problem with the axle alignment or differentialnoise. The dashed amplitude spikes 108 a′-108 c′ refer to amplitudespikes that are consistent with a driveline that has a fault or problemassociated with axle alignment or differential noise. The amplitudespikes 108 a′-108 c′ associated with a fault or problem are greater thanthe amplitude spikes 108 a-108 c associated with normal drivelineoperation.

Referring to FIG. 2E, a driveline also has a predictable peak amplitudespikes at orders 1-2-3. The peak amplitude decreases as the orderincreases until the harmonics are insignificant compared to systematicnoise. The solid line amplitude spikes 110 a-110 c refer to amplitudespikes that are consistent with a driveline that does not have a faultor problem with drive-shaft balance or a universal joint. The dashedamplitude spikes 110 a′-110 c′ refer to amplitude spikes that areconsistent with a driveline that has a fault or problem associated withthe balance of the drive-shaft or the universal joint (such as theuniversal joint being loose). The amplitude spikes 110 a′-110 c′associated with a fault or problem are greater than the amplitude spikes110 a-110 c associated with normal driveline operation.

Accordingly, the use of the spectrum analysis 48 a, 48 b, 48 c providesthe benefit of identifying and analyzing repeating signals. In sum,rotating elements on the vehicle have predictable repeating orders. Byanalyzing the amplitude spikes associated with these repeating orders,one can determine if a fault has occurred by comparing the currentspectra with spectra known to represent a rotating element that isoperating properly (without faults).

In one embodiment, the determination of whether a fault or problemexists is accomplished through a series of fault detects 50 a, 50 b, 50c, associated with each rotating element 30 a, 30 b, 30 c. As indicatedabove, when analyzing the spectra of a particular rotating element on avehicle, it has been discovered that a fault or problem can be detectedif the peak amplitude is higher than its normal operation. Thus, in oneembodiment, a predetermined threshold may be associated with eachabove-described condition.

The predetermined threshold can be implemented in a number of ways. Forexample, one embodiment includes an integration method to determine thearea of the amplitude spikes for the spectra. A value for thepredetermined threshold can be set that is slightly greater than thearea of the amplitude spikes that would exist for a rotating elementthat is operating properly (without faults). In other words, thepredetermined threshold should represent an acceptable value of the areaof the amplitude spikes before a fault or problem is detected with aparticular rotating element. If the area beneath the amplitude spikes(under analysis) is greater than the predetermined threshold, a faultexists with the rotating element. If the area beneath the amplitudespikes (under analysis) is less than the predetermined threshold, nofault exists with the rotating element.

In another embodiment, the predetermined threshold represents anacceptable maximum height for the amplitude spikes within the spectra.Here, the predetermined threshold is a maximum height (or value)slightly greater than a height of an amplitude spike that would existfor a rotating element that is operating properly (without faults). Whenthe amplitude spikes (under analysis) are greater than the predeterminedthreshold, a fault exists with the rotating element. In eitherembodiment, a different predetermined threshold would need to bedetermined for each type of rotating element and for each type ofproblem that may possibly exist for that rotating element. Thepredetermined thresholds may be installed by the manufacturer and basedon the type and design of the vehicle. The predetermined thresholds mayalso be determined from historical data on a fleet of vehicles of thesame make and model of vehicle.

In sum, when the amplitude spikes are at or below a predeterminedthreshold, the vehicle is determined to have no faults or problems.However, when the amplitude spikes are above the predeterminedthreshold, the vehicle is determined to have a fault or problem.

It is noted that the predetermined thresholds described herein may varybased on the speed of the rotating element. Accordingly, in oneimplementation of the present invention, each fault detect 50 a, 50 b,50 c contains a look-up table that can be indexed by the currentrotational speed of the rotating element 30 a, 30 b, 30 c. For thisimplementation, the fault detects 50 a, 50 b, 50 c need to have accessto the data received by the controller 26 from sensors 56 a, 56 b, 56 c.

In another implementation, the fault detects 50 a, 50 b, 50 c includehistorical averages of acceptable amplitude spikes for a particularrotating element. For example, if the diagnosis sampler 24 is samplingthe vehicle cabin at regular intervals during operation, a historicalthreshold average can be developed for each rotating element. In thisembodiment, the controller 26 stores in memory the amplitude spikes fordifferent rotational speeds of the rotating elements 30 a, 30 b, 30 c todevelop the historical threshold average. After an acceptable historicalthreshold average has been compiled, the fault detects 50 a, 50 b, 50 cwould then compare the existing amplitude spikes at a specific time tothe historical threshold average at the existing rotational speed. Ifthere was a sharp contrast between the existing amplitude spikes and thehistorical threshold average, then a fault or problem would be detectedby the controller 26.

If a fault or problem is determined by the controller 26, a fault signal62 may be provided to the user of the vehicle. In one embodiment, thefault signal 62 is provided to the electronic control unit (ECU) 32 ofthe vehicle. In this embodiment, the ECU 32 is connected to a userdisplay panel that notifies the user of the vehicle that a fault orproblem exists with a particular rotating element 30 a, 30 b, 30 c.

In another embodiment of the present invention, as shown in FIG. 3, thefault detection system 20 is used in connection with a Telematicssystem. The Telematics system includes a fault detection system 20(within a vehicle 70) and a service center 80.

The fault detection system 20 and the service center 80 may communicatewith each other via wireless communications. The wireless communicationsare illustrated in FIG. 3 by communication arrows A and B. Communicationarrow A may represent a communication by the user of the vehicle 70asking the service center 80 for help in analyzing a problem with thevehicle 70. Communication arrow A may also represent a communication bythe fault detection system 20. This communication could be a faultsignal 62 generated by the controller 26. Alternatively, the controller26 may directly send the synchronized envelopes 60 a, 60 b, 60 c or rawspectra data directly to the service center 80. The service center 80would then perform the fault detect functions. The advantage of thisapproach is that it allows the flexibility of changing the predeterminedthresholds based on historical data from fleet studies on vehicles withthe same make and model.

Communication arrow B may represent a communication by the servicecenter 80 instructing or informing the user of the vehicle 70 of thetype of fault or problem that may appear to exist with the vehicle 70.In a further embodiment, the diagnosis sampler 24 may be configured totake a sample of the audio within the cabin of the vehicle on demand bythe service center 80 through communication arrow B.

As shown in FIG. 3, in one embodiment, the communications A and B may bea cellular wireless communication that is sent through the publicswitched telephone network (PSTN) 82, a cellular network 84, and a basestation antenna 86. Those of ordinary skill in the art, having thebenefit of this disclosure, will appreciate that many possible wirelesscommunication methods may be used for communications between the vehicle70 and the service center 80. In one embodiment, the communications arevia a cellular wireless communication such as AMPS, CDMA, GSM, or TDMA.The transmission between the vehicle 70 and the service center 80 mayalso be made by other wireless communications such as satellitecommunications.

Having the fault detection system 20 wirelessly connected to a servicecenter 80 has several benefits as will be apparent from the followingdescription. The user of a vehicle 70 having the fault detection system20 may hear a noise or believes that the vehicle 70 is not respondingproperly. The user of the vehicle 70 may push a button in the vehicle 70to establish a wireless communication with the service center 80. Theservice center 80 receives the fault signals 62 from the vehicle 70 viathe wireless communication device 36 (as shown in FIG. 1). The servicecenter 80 may then look at the fault signals 62. If there is a fault orproblem, the service center 80 may inform the user of the vehicle 70 ofthe apparent problem. For example, it may appear from the fault signals62 that there is a severe misalignment problem with the axle. Theservice center 80 may then instruct the user of the vehicle that thevehicle should be taken (or even towed) to a car facility immediately.Alternatively, it may appear from the fault signals 62 that there is aproblem with the HVAC fan or blower. The service center 80 may theninform the user of the vehicle 70 that the problem does not appear to beserious but instruct the user to turn off the air conditioning.

The above description of the present invention is intended to beexemplary only and is not intended to limit the scope of any patentissuing from this application. The present invention is intended to belimited only by the scope and spirit of the following claims.

What is claimed is:
 1. A fault detection system for determining whether a fault exists with a rotating element in a vehicle, the fault detection system comprising: a transducer located in the vehicle for converting sounds to an electrical signal, the electrical signal comprising a noise component generated from the rotating element; a diagnosis sampler, connected to the transducer, for providing a sample of the electrical signal from the transducer; a sensor for obtaining data relating to the rotating element; a controller, connected to the diagnosis sampler and the sensor, having a synchronous resample, a spectrum analysis, and a fault detect, the synchronous resample having the capability of synchronizing the sample of the electrical signal with the data from the sensor to form a synchronized envelope, the spectrum analysis having the capability of forming a spectra from the synchronized envelope, the spectra being associated with the noise component generated from the rotating element, and the fault detect having the capability of determining from the formed spectra whether the fault exists with the rotating element.
 2. The fault detection system of claim 1, wherein the transducer is a microphone within a cabin of the vehicle.
 3. The fault detection system of claim 1, wherein the electrical signal converted by the transducer is an analog signal and the sample provided by the diagnosis sampler is a digital signal.
 4. The fault detection system of claim 1, wherein the spectrum analysis of the controller includes a fast Fourier transform.
 5. The fault detection system of claim 1, wherein the fault detect of the controller includes a comparison between an amplitude of the formed spectra and a predetermined threshold.
 6. The fault detection system of claim 5, wherein the predetermined threshold represents an area of an amplitude of a spectra where the rotating element does not have a fault.
 7. The fault detection system of claim 5, wherein the predetermined threshold represents a maximum allowable height of an amplitude of a spectra where the rotating element does not have a fault.
 8. The fault detection system of claim 1, wherein the controller further has an envelope detect having the capability of detecting an envelope of the electrical signal from the diagnosis sampler prior to the formation of the synchronized envelope.
 9. A method for detecting a fault associated with a rotating element in a vehicle, the method comprising the steps of: sampling an electrical signal from a transducer in the vehicle, the electrical signal comprising a noise component generated from the rotating element; synchronizing the electrical signal with data from a sensor associated with the rotating element to form a synchronized envelope associated with the rotating element; forming a spectra from the synchronized envelope, the spectra being associated with the noise component generated from the rotating element; determining from the formed spectra whether the fault exists with the rotating element.
 10. The method of claim 9, wherein the transducer is a microphone within a cabin of the vehicle.
 11. The method of claim 9, wherein the step of forming the spectra from the envelope includes a fast Fourier transform.
 12. The method of claim 9, wherein the step of determining whether the fault exists includes a comparison between an amplitude of the formed spectra and a predetermined threshold.
 13. The method of claim 12, wherein the predetermined threshold represents an area of an amplitude of a spectra where the rotating element does not have a fault.
 14. The method of claim 12, wherein the predetermined threshold represents a maximum allowable height of an amplitude of a spectra where the rotating element does not have a fault.
 15. The method of claim 9 comprising the further step of sending a fault signal to an electronic control unit of the vehicle when it is determined that a fault exists with the rotating element.
 16. The method of claim 9 comprising the further step of detecting an envelope of the electrical signal, the envelope comprising the noise component generated from the rotating element, the step of detecting the envelope of the electrical signal performed prior to the step of synchronizing the electrical signal.
 17. The method of claim 9 comprising the further step of transmitting a fault signal to a service center representing whether the fault exists with the rotating element.
 18. A method for detecting whether a plurality of faults exist with a plurality of rotating elements in a vehicle, the method comprising the steps of: sampling an electrical signal from a transducer in the vehicle, the electrical signal comprising a plurality of noise components generated from the rotating elements; synchronizing the electrical signal with data from a plurality of sensors associated with the rotating elements to form a synchronized envelope associated with each rotating element; forming a plurality of spectra from the synchronized envelopes, each spectra being associated with one of the noise components generated from the rotating elements; determining from each of the plurality of formed spectra whether one of the faults exist with one of the rotating elements.
 19. The method of claim 18, wherein the transducer is a microphone within a cabin of the vehicle.
 20. The method of claim 18, wherein the step of forming the plurality of spectra from the synchronized envelopes includes a fast Fourier transform.
 21. The method of claim 18, wherein the step of determining whether one of the faults exist includes a comparison between an amplitude of the formed spectra and a predetermined threshold.
 22. The method of claim 18 comprising the further step of sending a fault signal to an electronic control unit of the vehicle when it is determined that one of the faults exist with one of the rotating elements.
 23. The method of claim 18 comprising the further step of detecting an envelope of the electrical signal, the envelope comprising the noise components generated from the rotating elements, the step of detecting the envelope of the electrical signal performed prior to the step of synchronizing the electrical signal.
 24. The method of claim 18 comprising the further step of transmitting a fault signal to a service center when it is determined that one of the faults exist with one of the rotating elements. 